The bacterial infection is caused due to the Pathogenic bacteria such as genus Streptococcus, Staphylococcus, Mycobacterium, Helicobacter, Pseudomonas, Enterococcus, Escherichia etc.
Among the pathogens S. aureus is the most common species of staphylococcus to cause Staph infections. The said pathogen is also referred as “golden staph” or “Oro staphira”, which is Gram-positive coccal bacterium. Staphylococcus aureus is a part of the skin flora found in the nose and on skin. “S. aureus” can cause a range of illnesses from minor skin infections, such as pimples, impetigo, boils (furuncles), cellulitis folliculitis, carbuncles, scalded skin syndrome and abscesses, to life-threatening diseases such as pneumonia, meningitis, osteomyelitis, endocarditis, toxic shock syndrome (TSS), bacteremia and septicemia.
Enterococcus faecalis is a nonmotile, gram-positive, spherical commensal bacterium, inhabiting the gastrointestinal tracts of humans and other mammals. E. faecalis is listed as the first to the third leading cause of nosocomial infections which may mostly occur after surgery of the abdomen or a puncturing trauma, also due to increased use of IV's and catheters. Further it cause urinary tract infections, bacterimia, endocarditis, meningitis, and wound infections along with many other bacteria.
One of the bacterial diseases with highest disease burden is tuberculosis, caused by the bacterium Mycobacterium tuberculosis. 
Tuberculosis causes millions of fatalities each year and in combination with HIV is proving to be a significant threat to global health. Although several new promising drug candidates are under consideration for clinical use, the increasing incidences of multi-drug resistant (MDR) and extensively drug resistant (XDR) strains of Mycobacterium tuberculosis (Mtb) necessitates new strategies for targeting this pathogen.
SO2 is an environmental pollutant that is toxic to humans at elevated levels; chronic exposure to SO2 induces oxidative stress and asthma-like symptoms. SO2 has diverse documented biological effects including damage to biomacromolecules such as proteins, lipids and DNA. Oxidation of sulfur dioxide by metal ions produces sulfur trioxide radical, which possibly mediates damage to biomacromolecules. Furthermore, sulfite, the anionic form of sulfur dioxide can break disulfide linkages to produce S-sulfonates. Thus, SO2 can participate in oxidative as well as reductive processes under physiological conditions and may perturb redox equilibrium in cells. Recently, alteration of redox homeostasis in Mtb has been proposed as an effective mechanism for targeting this bacterium.
Further Pat Henderson et al. in Practical winery and vineyard Journal 02/2009 discloses broad-spectrum antimicrobial agent, sulfur dioxide, having an inhibitory effect on a wide variety of microorganisms.
Thus, sulfur dioxide may have diverse mechanisms for cytotoxicity induction and multiple biological targets. Despite such well-documented deleterious effects, SO2 (in the form of bisulfite, metabisulfite and sulfite) has also been routinely used as an antibiotic and antioxidant in the food industry, in wineries and is well tolerated in most individuals. Barring certain individual cases of allergies, sulfur dioxide is well-tolerated in humans; in certain meats that are consumed on a daily basis, SO2 levels can reach up to 450 mg kg−1.9. Thus, it was envisaged that the susceptibility of bacteria to the deleterious effects of SO2 could be exploited to develop new SO2-based tuberculosis drug candidates. To tap its therapeutic potential and possibly to avoid undesirable side effects, controlled delivery of SO2 is necessary.
The poor bioavailability of gaseous sulfur dioxide precludes its usage for therapeutic purposes and the use of complex inorganic sulfite mixtures, typically used to generate SO2 in biological systems, suffers from a lack of control of rate and amount of SO2 generated. As there were no reliable SO2 sources available, the present inventors proposed to develop organic donors of sulfur dioxide with tunable release profiles in order to evaluate their efficacy as against bacterial infections.
It has been reported in Tetrahedron Letters 38, (33), 1997, 5831-5834 by Fukuyama et al. that amines can be protected by the reaction with 2,4-dinitrophenylsulfonyl chloride (DNsCl) as 2,4-dinitrophenylsulfonamides, wherein deprotection of such amides was carried out by thiols such as 2-mercaptoacetic acid in basic medium to produce amines in good yields (cf below scheme), wherein a byproduct of these deprotection reactions was sulfur dioxide.

Though, the release of SO2 from the deprotection of 2,4-dinitrophenylsulfonamides is known from the above article, the thiol activated 2,4-dinitrophenylsulfonamides analogs as source of SO2 with tunable release profile which significantly inhibits the growth of bacterial infection is not yet reported.
2,4-Dinitrophenylsulfonamides have also been used in thiol detection systems for environmental and biological applications.
Xiaoqiang Chen et al. in Chem. Soc. Rev., 2010, (39), 2120-2135 focuses on the fluorescent or colorimetric sensors for thiols according to their unique mechanisms between sensors and thiols, including cleavage of sulfonamide and sulfonate ester by thiols, cleavage of disulfide by thiols, wherein the thiols are selected from cysteine, homocysteine and glutathione.
Furthermore, variation of the groups on the amine may provide a handle for modulating SO2 release profiles. Unlike mammalian cells, Mtb does not contain glutathione (GSH) but mycothiol (MSH) as the primary thiol in millimolar concentrations.
Gerald L. Newton et al. in Journal of bacteriology, vol. 178, no. 7 Apr. 1996, 1990-1995 discloses that MSH production is confined to actinomycetes and shows that mycobacteria, including Mycobacterium tuberculosis, produce high levels of thiol (MSH).
MSH is critical for the maintenance of redox homeostasis and alteration of thiol-levels could induce stress to Mtb. Upon reaction with a 2,4-dinitrophenylsulfonamide, MSH is expected to be arylated to generate sulfur dioxide intracellularly. Thus this two-pronged strategy of introduction of SO2 and a thiol-depleting agent could inhibit Mtb growth.
Therefore the present inventors have developed organic donors/prodrugs of SO2, i.e. 2,4-dinitrobenzenesulfonamides analogues with tunable release profiles of SO2 in order to evaluate their therapeutic efficacy against bacterial infections which remains objective of the present invention.